rs518147, also known as -697G/C, is a SNP in the 5-hydroxytryptamine (serotonin) receptor 2C HTR2C gene.

A study of 107 patients with schizophrenia being treated with olanzapine reported a protective effect against weight-gain from the (C) allele of this SNP; fewer patients (of 28) with a rs518147(C) allele had a body mass index increase of >=10% (p=0.0006), whereas (G;G) homozygotes did. This effect may also involve nearby SNP rs3813929.[PMID 19434072]